Centrifugal pump.



E. A. MARSH. GENTRIFUGAL PUMP. APPLICATION FILED DEG.23, 1910.

Patented May 14, 1912 5 SHEETS-SHEE T l.

E. A. MARSH. GENTRIFUGAL PUMP. APPLICATION FILED DEG. 23, 1910.

Patented-May 14, 1912.

5 SHEETS-SHEET 2.

INVENTOR. .X W 4.40

A TTORNEK .Qnhll I- I I 1 bag/55555 W E. A. MARSHJ LENTRIFUGAL PUMP) APPLIOATION FILED DEG. 23, 1910.

LUQG, TL 01 w Patented Ma 14,1912.

5 SHEETS-SHEET a.

Q fis Z E. MARSH. GENTRIFUGAL PUMP. APPLIOATION FILED DEO.23, 1910.

Patented May 14, 1912.

5 SHEETS-SHEET 4.

v E. A. MARSH.

GENTRIPUGAL PUMP.

APPLICATION FILED DEC. 23, 1910. 1,026, 1 01 Patented May 14, 1912 Jlr I l l 11V VLN TOR.

A. A TTORNE Y.

ELON A. MARSH, OF DETROIT, MICHIGAN.

CENTRIFUGAL PUMP.

Specification of Letters Patent Patented May 14, 1912.

Application filed December 23, 1910.- SerialtNo. 599,036.

Detroit, county of Wayne, State of Michigan, have invented a certain new and useful Improvement in Centrifugal Pumps, and declare the following to be a full, clear, and

exact description of the same, such as will enable others skilled in the art to which itpertains to make and 'use the same, reference being had to the accompanying drawings, which forma part of this specification.

This invention relates to. centrifugal pumps and its object is an improved pump of this class in which the duty performance per unit of power employed is much greater than has heretofore been realized. By reason of the great frictional resistance characteristic of this type of machine, centrifugal pumps have not, in the past, shown a suliiciently high rate of mechanical efficiency as to supersede other types of greater bulk and complication of parts and that are more costly both in construction and maintenance. If this frictional resistance can be reduced without a corresponding reduction in the amount of useful work, it seems evident that a great gain in efficiency may be realized. One of the best types oficentrifugal pumps, and generally speaking, the one showing the highest efiiciency is'the closed or box impeller type in whichthe' impeller wheel rotates ina chamber formed by the cylinder heads and the cylindrical wall of the discharge channel. This chamber fills with water during the operation of the pump and the skin friction produced by'the rapid rotation of the impeller wheel in this waterpacked chamber is the principal cause 'of the low output per unit of power emwater from the chamber that may accumulate therein by seepage.

These and other objects and novelties of the invention are hereinafter more fully described and claimed.

In the drawings-Figure 1 is a side elevation of a centrifugal pump embodying my invention. One of the cylinder heads and inlet pipe connecting therewith being removed to more clearly show the impeller wheel. Fig. 2 is a plan View of the pump showing the inlet chamber in section. Fig. 3 is a vertical longitudinal section of the pump, the dotted lines diagrammatically showing the relation of some of the parts. Fig. 4: is an enlarged sectional detail of a part of the impeller wheel and chamber in which it rotates. Fig. 5 is a detail showing the method and means employed in packing the shaft to prevent a leakage of air into the inlet chamber of the pump. Fig. 6 is a detail of the shaft bearmg. Fig. 7 is a detail showing one of the outlet orifices in the wall of the discharge channel.

Similar letters refer to similar parts throughout the drawings and specification.

A indicates an impeller wheel of the closed or box type which is keyed to the shaft S mounted in bearings Z2, 6 carried by the cylinder heads C, C. The cylinder heads are bolted to the discharge channel B in the usual manner. The discharge channel B is spiral in form as shown in Fig. land has a circular, central opening within which is located the impeller wheel whose periphery is practically in contact with the inner circular wall of the channel. This circular wall has a passageway 79 through which the water from the impeller wheel enters the channel 13. The impeller wheel A is provided with vanes o and hubs h, h integral with the side walls w. The hubs form the inlet orifices into the wheels as shown inFig. 3. The cylinder heads are each provided-with central openings into which the hubs h extend and surroi'lnding r the hubs are circular channels 0, c in the cylinder heads. The walls'ofthe cylinder heads conform somewhat closely to the shape of the impeller wheel and the cubical con tents of the chamber surrounding the wheel is consequently small. Each cylinder head is proyided with a chamber 0 into which the inlet pipes I, I lead The inlet pipes with air under pressure equal to the dis- .discharge channel B in a manner usual with this typeof machine.

In order that the chamber 8 surrounding the impeller wheel may at all times be filled charge pressure of the pump, ,1 have arranged a'tank or cistern T on the same foundation with the pump but at such a height than an imaginary line passing through the shaft center of the pump would divide the tank into two practically equal parts. Connected with the top of the tank is a pipe 9 which leads to the chamber 8 surrounding the impeller wheel. Connected to the bottom of the tank is a pipe 9 which leads to the discharge channel B. Consequently whatever the discharge pressure of the pump is, it is communicated,by means of the pipe 9 to the water in the tank T and therefore to the air in the upper part of the tank and in the chambers surrounding the impeller wheel. As the pressure in the discharge channel increases or diminishes, due to' va-' riation' in speed of the impeller or other cause, the air pressure in the tank and the chamber 8 varies accordingly,

In order that the relative quantity of air and water inthe tank maybe observed and the conditions known under which the pump is working, the tankT is provided with a gage glass If the water stands much above the center of the tank, too small a quantity of air is indicated for the pressure at which the pump is working. If the water is much below the center of the tank, to o great a quantity of air is indicated for the, pressure at which the pump is working. To keep the conditions described in equilibrium, the tank T, is provided with a pipe 72 leading thereinto provided with a valve '0 to which is connected the pipes p and 10 The pipe pflis to be connected with an air compressorfor other source of supply and the pipe isopen to atmosphere. If too small .a quantity-of air is indicated in the system,-

the valve 41 is turned to allow air from the compressor or storage tank to flow into the tank T. If too great a quantity of air is indicated, the valve o is turned to allow an escape of the desired quantity through the pipe'p The system, however, would be practically self sustaining and the'above de scribed means of establishing equilibrium would only be utilizedfat the'time of startdottedlines in Figl ingfor to overcome excess leakages that might occur. The cubical capacity of the tank T should be greater than thatof the impeller chamber 5. By filling the chamber a with air under pressure as described, the impeller wheel rotates. without frictional resistance on the side walls w thereof and the cost of operation will be so reduced that the output per unit of power employed compares very favorably with that of pumps of the reciprocating type.

Any very perceptible leakage of air from the chamber is undesirable, therefore the chanrels'c, '0 heretofore described as surrounding the hubs h of the impeller wheel, are connected to the discharge channel B by means of the pipesl0, as shown in Fig. 31 and thereby filled witlr water under pres sure. To preclude the possibility of the es-. cape of air from the chamber a into the suction chamber 0 the pressure of water in the channels 0, 0 should be slightly greater than the air pressure in the chamber so that water will leak into the chamber. To accomplish this, the passage 0 -in the wall of the channel B, to which the pipe' 7c connects as shown in Fig. 7 should pass therethrough at an acute angle to the direct-ion of flow through the channel with the inner end of the passage facing, as nearly as possible, the flow in the channeL- The pressure in the pipes 70', It" and the channels 0, 0 will thus be augmented by the velocity of the flow through the channel B. The hubs it run very nearly in contact with that part of the cylinder heads C which surrounds them as heretofore described, consequently leakage of-water from the channels c, a into the chamber 8 and suction cham. her 0 Wlll not be very great. Alezikage into the chamber a will occur as there is no pressure insaid chamber to counteract the pressure in the channels 0,'c'. I

To prevent a leakage ofairfrom-the impeller chamber into the passageway p in the discharge channel, the 'eircular wall' W of the channel B is rovided with grooves u, u inalincment with the peripheral edge of the side walls w, w of the 1m eller wheel.

The grooves fill with water un or pressureand prevent any, serious leakage of air from the chamber; These grooves would as offectually perform their function if they were formed in the peripheral edge of the side walls w of the impeller and might alsobe of other shapes than as shown without depart;

ing from the spirit of this invention.

As heretofore described and as shown particularly in Fig.- 1 and diagrammatically by 3. the center of the tank Tfis practically in line with the shaft of than the pressure at the. top or highest'.

point of the impeller wheel and is .le-ssthan the pressure at the bottom or lowest point the pump. .The pressure'of water in the of the impeller wheel. This is due to the difference in hydrostatic head between the several points. The pressure inthe tank T is the pressure due to the combined discharge pressure of the pump and the hydrostatic head at the center line. This is also the pressure of the air in the chamber .9. It will thus be seen that the pressure of air in the impeller chamber is greater than the pressure of water at the top of the impeller Wheel and is less than the pressure of the Water at the bottom of the impeller wheel.

There is, therefore, a tendency for the air in the top of the impeller chamber to leak through the interstice between the edges of the impeller wheel and the Wall W of the channel B into the passageway 72. There will also be a tendency for the Water to leak into the chamber a through the space between the wall and the impeller at the bottom of the wheel. As the impeller fits closely in the circular opening in the spiral casing, the leakage of water into the impeller chamber is of little importance because of its small volume. The leakage of air from the chamber, however, is of greater importance and it is to effectually prevent this that the grooves u, u are provided. These grooves fill with water at the bottom of the wheel. due to the. greater pressure of water at this point as heretofore described. The Water thus accumulated revolves with the impeller wheel by reason of its frictional contact therewith but not at the same speed because of its contact with the non-rotative surface of the Wall W of the channel 13.

Air will also accumulate in the groove at the top of the impeller wheel, as heretofore shown, and will be carried around with the the chamber where the wheel. As indicated in Fig. 4 at z, the air that may accumulate in the grooves u, u

at the top of the wheel will be on the air chamber side and in contact with the pe ri her of the im eller wheel to a reater P .V P 1-,

extent than with the groove itself. The reaon for this is that the centrifugal force of the water revolving in the groove will tend to keep the groove filled, and, at the point where the air pressure may be great enough, the air Wlll tend to seep out of the chamber in contact with the peripheral surface of the impeller. As the air revolves with the im peller, it will, in its travel therewith, be gradually forced back into the chamber 8 as it approaches the bottom thereof and be entirely removed from the groove and the interstlce between the nnpeller and its casing when it has arrived at the bottom of water pressure is the greatest.

-'llhe volume of water whichmay escape through the interstice is proportional to the area of said intcrsticc modified by its length and the difference in hydrostatic pressure between the air chamber 8 and the groove Water in the chamber a Whatever the difference. in hydro-.

its volume is lessened by said reversal and is entirely abated when the impellerruns at high speed. To illustrate, let it be supposed that, at some certain, slow speed of the impeller wheel, water leaks through the interstice into the impeller chamber at the bottom of the wheel at a speed of fifty feet.

per second; the air in the impeller chamber having a corresponding tendency at the top of the wheel. As the air and water in the interstice revolve with the impeller Wheel, as heretofore stated, the differences in hydrostatic pressure encountered by the air and water in their travel with the impeller will alternate the direction of flow of both the air and'water so that the volume of leakage in either direction is proportionate to the duration of said alternation, which is determined by the speed of revolution of the impeller wheel. W hen the speed of the im peller has become so great that the direction of the tlow or water through the interstices is reversed at a rate of speed equal to said flow of fifty feet per second divided by the length of the interstice, the leakage is entirely abated and a state of equilibrium produced which is automaticallv maintained as long as the impeller runs at the proper speed. Any speed of the impeller wheel greater than that above described will lessen the distance of travel of the water during said alternation in the direction of flow.

through'the interstice. If, when a state of equilibrium is reached, the water travels the entire length of the interstice and back during an alternation in the direct-ion of flow therethrough, then, if the speed of reversal is increased, the water can only travel a part of said distance and back as the time during which it may travel in either direct-ion is lessened.

, To remove the watet that may seep into the chamber a at the periphery of the-impeller and at the hubs h, as heretofore shown, a trap L is provided connected, by means of the pi m, to the chamber a at the bottom 0 thedischarge casing B. This chamber is connected to the air chamher 8 bychannels z, i shown clearly in Fig. 3 and indicated by dotted lines in Fig. 1. The trap is provided with a float f pivoted to the side Wall of the trap chamber and connected to a valve in the pipe 15 which leads to one of the suction pipes I. The pipe 25 and the valve therein are below the water level in the trap and are th'usefiiectu ally water sealed which prevents an escape of air from the chamber 8. Any excess of will flow into the trap through the channels 11, z'and the pipe m and raise the float f. The raising of the float opens theivalve in the pipet and the pressure of the, the chamber 8 and the 5 upper part of the trap chamber will force the water out of the' trap into the suction pipe I through the pipe t. As the waterv Hcsscsbut'of the trap, the float drops and closes the valve in the pipe t. The removal of water from the chamber 3 is, therefore, entirely automatic and requires no attention other than to keep the trap in proper work-. ing condition. w

In order that air may be prevented from ls being drawn intothe suction chamber 0 through the stuffing box in the cylinder head in which the shaft S is located, a pack- Ting for the shaft is provided as shown in 'Fig. The shaft is provided with a bushing j and surrounding this is the packing material .J in the stuffing box J The stuffing box is provided with a gland j of the ordinary type. At or near the center of the box and encircling the shaft are two flat rings 7*, '1. betweenv which is a coiled spring 1%. 'llhe spring holds the rings-apart and leading to theannular channel thus formed is a passageway r in the stuffing box. to which a pipe r may be connected, which communicates with the discharge channel B at any convenientpoint as shown by dotted lines in Fig. 3. The channel'betwcen the rings t", r is thereby filled, with water under pressure and the packing thus compressed to such'degree as to preclude the possibility of air leaking therethrough into the suction chamber. b

By reason of the great internal, pressure developed'in this type of pump, he cylinder heads are subjected to severe strain which maytend to bindthe shaft in the hearings d, d carried by the cylinder heads. To obviate this ditiiculty, the bearings are formed with an annular channelq in which the ring q of the journal Q loosely fits. The journal isthus swiveled int-he bearing and any irregularities in thealinement of the bearing, due. to excessive strai on the 'cylindefhead, 'is compensated for and the shaft may revolve without bindin The shaft maybe oiled by ring oilers of the ordinary type as shown. T ,The tank T, instead of being arranged as Y shown, may be formed in the cylinder headsas aseparate compartment but integral with them. J. i I Various other departures from the structure herein-shown may be made without departing from the spirit of this invention.

Having thus briefly described my in 'vcntion and its method of operation, What I claim isv p A w p 1. In a centrifugal pump, an impeller wheel of the closed or box type, a chamber 65 for filling said chamber with air under pressure, means for preventing a leakage of air from the chamber, and a trap for removing liquid from the chamber.

2. In a centrifugal pump, an impeller wheel of the closed or box type, a chamber in which the impeller Wheel revolves, means for filling the chamber wit-h air under pressure corresponding with thedischarge pres sure of the pump, means for preventing a leakage of air from the chamber.

. 3; In a centrifugal ppmp, {an impeller wheel of the closed or box type, a Chamber in which the impeller wheelrevolves, means for filling the chamber with air under pressure, and means for preventing a leakage of air from the chamber. 0

4. In a centrifugal pump, an impeller wheel of the closed or box-type, a chamber in which the impeller wheel revolves, means for filling the chamber with air under pressure, means for preventing a leakage of air from the chamber and of producing a leakage of water into the chamber, and means for removing the water from the ClIlUTI JOI'.

5. In a centrifugal pump, an impeller of the closed or box type, a chamber in which the impeller revolves, means for filling the chamber with air, said means including an external source- 0t supply, means whereby the' discharge pressure of the pump is commu'nicated to the air in. the chamber, and means for preventing a leakage of air from the chamber.

6. In a centrifugal pump, an impeller wheel of the closed or box type, a chamber filled with air under pressure in which the impeller wheel revolves, automatic means for varying the air pressure, and means for preventing a leakage of air from the chamher.

7. In a centrifugal pump, an air chamber in which the impeller wheel revolves, and a incommunication with both the air cha1nher and the discharge channel of the pump whereby the pressure in the discharge channel is communicated to the air in the chamber. I

' 8. In a centrifugal pump, an air chamber in which the impeller wheel revolves, an an tight compartment in, communication with the aI-ir chamber, means for producing pressure therein, corresponding with the discharge pressure of the pump.

'9. In a centrifugal pump, an air chamber in which the impeller revolves, an air tight compartment in communication with the air chamber, and means for producing pressure therein automatically varying 1n accord with the discharge pressure of the puinp,

-! 10., In a centrifugal pump, an impeller wheel of the closed orbox type, an air chamb'er in which the impeller wheel revolves, an

in which the impeller Wheel revolves, means air I tight compartment in communication .l (iii tank or compartment exterior of the pump llh with the air chamber, means for altering the volume of air in the compartment and chamber, and means for compressing the air in the compartment and chamber to correspond with the discharge pressure of the pump. 11. In a centrifugal pump, an impeller wheel of the closed or box type, a chamber in which the impeller wheel revolves, means for filling the chamber with air under pressure, means for preventing a leakage of air from the chamber and of producing a leakage of Water into the chamber, and means for removing the water from the chamber; said means including a water sealed, fioat operated valve controlling the outlet from "the chamber.

containing air under pressure, hubs for said impeller Wheel extending through the walls of the impeller chamber, circumferential grooves in the walls of the chamber facing and surrounding the hubs of the impeller wheel, and channels connecting said grooves with the discharge-chamber of the pump;

the orifices in the discharge chamber which form the inlets to the channels being arranged to face the flow'in the discharge chamber whereby said grooves have a pressure head greater than the hydraulic head, substantially as and for the purpose described. r

' 14. In a centrifugal pump having a closed or box impeller wheel mounted in an air chamber formed by the cylindrical wall of the discharge chamber andthe walls of the cylinder heads, circumferential grooves in said cylindrical wall facing the peripheral.

edges ofthe' sidewalls of the impeller wheel said grooves forming reservoirs for water that may accumulate therein by leakage from the discharge chamber and acting as secondary impellers which receive and discharge said leakage by reason of the diiferences in hydrostatic head encountered by the 'water in its travel around the impeller Wheel, substantially as shown and described.

15. In a centrifugal pump having an impeller Wheel which operates in a chamber containing air under pressure, said chamber being formed by the cylindrical wall of the discharge chamber of the pump and the walls of the cylinder heads, hubs for said impeller wheel extending through the Walls of the impeller chamber, grooves surrounding said hubs, and grooves surrounding the said chamber, a stufiing'box for the shaft carried by each of 'said'walls, packing material in each box, a centrally disposed ciroumferential channel in said packing, means for mamtaimng said channel in opposition to the pressure produced on the packing by the gland with which the stulling box-is provided, means for filling said circumferential channel with water under pressure, and swiveled bearings for said shaft carried by saidchamber walls.

17. In a centrifugal pump, an air chamber in which the impeller revolves, and an air tight compartment in communidation with both the air chamber and the discharge channel of the pump, whereby the pressure in the discharge channel is'eommunicated to the air in the chamber.

18. In a centrifugal pump, a chamber in which the impeller revolves, means for filling the chamber-with air under pressure, and means for automatically counteracting said pressure at the periphery and hub of the impeller thereby preventing a leakage of air from thechamber.

19. In a centrifugal pump, an impeller of the closed or box type, a chamber filled with air under pressure in which the impeller 'revolvcs, means whereby the pressure of the air is determined by the discharge pressure of the pump, said means comprising an air tight compartment in communication with both the air chamber and the discharge channel of the pump, and means external of the pump for introducing air into said air tight compartment 20. In a centrifugal pump, an air chamber in which the impeller revolves, means for producing pressure therein automatically va-ryingwith the discharge pressure of the pump, and means for preventing a leakage of air from the chamber.

21. In a centrifugal pump, an impeller wheel of the closed or box type, a chamber in which the impeller wheel revolves, means for filling the chamber with air under pressure, and means for preventing a leakage of air from the chamber comprising water packing grooves or channels surrounding the hub and the periphery of the impeller in communication with the discharge channel of the pump.

22. In a centrifugal pump, an impeller of the closed or box type, a chamber in which the impeller revolves, meansfor a trap for removing iliquid from the chamber, and

means for filling the' chamber With airilnder pressure.

23. In a centrifugal pump having an impeller of the closed or box type rotatable in a chamber, means for freeing the chamber of liquid by a volume of air under pressure,

and means for maintaining air in the chamher under a pressure equivalent to and varying With the discharge pressure of the pump, said means including a means for preventing a leakage of air from the chamber.

24. In a centrifugal pump having an impeller 0f the closed or box type rotatable in a chamber, means for filling the chamber With air under pressure, and means independent of the air pressure for freeing the chamber of liquid.

In testimony whereof I sign this specification in the presence of two Witnesses.

ELON A. MAR SH. 

